Apparatus for synchronizing actuators

ABSTRACT

An apparatus for synchronizing a plurality of actuators, comprising a pressure fluid source 15 associated with a setting device 6, with transmitters 10 of the movements of the operating members 5, and also with multichamber adding elements 17 equal in number to the actuators 4 to be synchronized. Each of the adding elements 17 includes an inlet chamber 36 associated with one of the actuators 4 and an outlet chamber 37 associated with the inlet chamber 36 and with a pressure fluid drain means 16, and further includes positive control chambers 24, 26 and 28 serving to increase the fluid supply through the inlet chamber 36 to the actuator 4 and negative control chambers 25, 27 and 29 serving to decrease the pressure fluid supply, the inlet chamber 36 of each adding element 17 being associated with one of the negative control chambers 25, 27 and 29 of the same adding element 17,  one of the positive control chambers 24, 26 and 28 of each element 17 being associated with the output of the setting device 6, while the output of the transmitter 10 of each actuator 4 is associated with such a number of negative control chambers 25, 27, 29 of the adding element 17 associated with the same actuator 4, which is one unit less than the number of the actuators 4 to be synchronized, and also with one of the positive chambers 24, 26, 28 of the rest of the adding elements 17.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to pneumatic and hydraulic control systemscomprising a number of actautors, and more particularly to methods ofsynchronizing actuators and apparatus for implementing the same.

Still more particularly, the present invention relates to methods of andapparatus for synchronizing two or more actuators of prime or secondarymovers operating in parallel into a common load.

The present invention can most advantageously be used in multiple-unittransport power plants comprising Diesel engines or turbines andproviding at the same time the operation of an electric generator.

2. Description of the Prior Art

At present the ships of various types are often equiped with two-unitDiesel power plants where the movers operate into a common load, viz.one propeller. In those cases, when two or more prime or secondarymovers operate into a common load it becomes necessary to provide equalload distribution between these units, especially when the load changes.Thus, for example, if the total load on the movers is sharply increaseddue to external reasons, each of these movers should continue tocontribute into the total load, its contribution being equal inmagnitude to that prior to the increase. It means that correlationbetween the contributions of individual movers to the total load shouldremain unchanged.

Equalization of the load is provided through correspondingsynchronization of the operation of the mover actuators, in particularfuel or any other energy supply regulators. The main reasons accountingfor unequal load distribution between the engines are the following:

unequal time of response to the change of the load in various movers or,in other words, unequal time constant of the movers;

unequal character of transmission, in actuators of different movers, ofa control signal applied to said actuators from the common settingdevice into useful movement of their operating members due tounavoidable deviations in geometrical dimensions of the elementsconstituting the actuators as well as due to their temporarymisadjustment, etc.;

unequal speed of transmission of control signals both through the commoncontrol circuit and through feedback circuits.

Unequal distribution of the load between the movers results in the lossof preset speed or moments and increased fuel consumption as well asunderloading or overloading of some movers and thereby their prematureware and even failure. The present invention is directed at providing amethod of synchronizing actuators and an apparatus implementing saidmethod ensuring uniform distribution of the common load between themovers.

Known to the art is a method of synchronizing actuators (Cf. USSRInventor's Certificate No. 496381, published in 1973), applied incontrol of mechanized tunnel shield. This method comprises the steps ofmeasuring in the process of the tunnel shield operation, the values ofdisplacement of the operating members, namely the rods of allhydrocylinders used therein with respect to a base point, derivingsignals corresponding to the displacement of each rod, separating out ofsaid signals the lowest one and separately comparing the obtainedsignals to derive a correction signal used for adjusting the position ofthe rod of each hydrocylinder through changing the supply of thepressure fluid to its operating volume, said correction signal beingproportional in magnitude to the difference between the signalcorresponding to the displacement of the rod of any hydrocylinder andthe signal corresponding to the shortest displacement of all the rodsrelative to the base point.

Synchronization of hydrocylinders in accordance with this method is acomplicated process requiring the sequence of the following procedures:

comparing the rod position of each hydrocylinder with the position ofthe base point;

selecting out of the displacement of the rods of hydrocylinders theshortest displacement;

deriving from several comparing devices control signals proportional inmagnitude to disagreement between the position of the rod of eachhydrocylinder and the position of the rod of the hydrocylinder deviatedby minimum value from the position of the base point.

Such intricate scheme of producing control action fails to providesufficient accuracy and synchronization speed of the actuators.

The apparatus implementing the afore-mentioned method comprises asetting device adapted to exert a common control action on the movementof the rod of each hydrocylinder, displacement transducers for the rodsof hydrocylinders and adjustable pressure fluid sources, each of saidsources being connected with one of the hydrocylinders through anindividual line accommodating an electrohydraulic regulator. In thisapparatus the output of each of the displacement transducer is connectedto one of the inputs of a means adapted to derive a signal of minimumerror between the position of the base point and the position of eachrod of hydrocylinders as well as to one of the inputs of one of the maincomparing devices, the other input of each said device being connectedto the output of the means of producing said signal, while the outputthereof being connected to the control input of one of theelectrohydraulic regulators. The output of each displacement transduceris connected, besides, to one of the inputs of one of the additionalcomparing devices, the other input of each said device being connectedto the output of the setting device and its output being connected toone of the pressure fluid sources.

Thus, this apparatus comprises a comparatively large number of elementsand therefore it is rather complicated in design. In the above apparatuseach hydrocylinder to be synchronized is associated with one pressurefluid source and with two comparing devices, one of which besides iscontrolled by the auxiliary means adapted to select minimum deviationfrom the position of the base point. As a result, the reliability andspeed of response of this apparatus are comparatively low. Moreover,application and potentialities of this apparatus are limited by thenecessity to use the base point.

Also known to the prior art is a method of synchronizing actuators (Cf.U.S. Pat. No. 3,772,884, published Nov. 20, 1973), which actuators arethe regulators of the prime movers driving a common load, each having amovable operating device providing fuel supply to the associated primemover. This method comprises the steps of measuring the movement of theoperating device of the regulators, corresponding in magnitude to thefuel supply and therefore the loads on the associated engines to derivesignals corresponding to the movement of each operating member of eachregulator, comparing said signals to derive a single signal which is theaverage of said signals followed by separate comparing each said signalcorresponding to the movement of each operating member of each regulatoragainst the signal corresponding to the average of said signals, andadjusting the position of the operating member of each regulator in adirection and by an amount proportional to the correction signal derivedfrom said comparison. The correction signal is produced in such a waythat it is proportional in magnitude to the difference between thesignal corresponding to the movement of the operating member of any oneof the regulators and the signal which is the average of movements ofthe operating member of all the regulators.

The apparatus implementing this method of synchronizing actuators,described in the afore-mentioned U.S. Pat. No. 3,772,884, comprises asetting device adapted to exert a common control action on the movementof the operating member of each regulator, a pressure fluid sourceassociated with transducers of the movement of the operating members ofthe regulators and with a comparing device adapted to produce a controlaction on the regulators and associated with the regulators and with thetransducers of the movement of the operating members of said regulators.The comparing device is a multichamber adding element having a housingaccommodating an axially movable stem and a spring-loaded valve whichcan be in contact with said stem. Secured to the stem are diaphragmsdividing the interior of the housing into positive control chambersproviding the movement of the stem in one direction in response to thepressure build up therein and into negative control chambers providingthe movement of the stem in the opposite direction. The housing alsoaccommodates an inlet chamber actuating the valve and thereby providingtransmission of the control action from the pressure fluid source to theactuators due to the movement of the stem in said one direction by thesum of the pressures in the positive control chambers exceeding the sumof the pressures in negative control chambers, and an outlet chambercommunicated with the inlet chamber and operatively associated with thefluid pressure drain means when the sum of the pressures in the negativecontrol chambers exceeds said sum in the positive control chambers. Thepositive control chambers of the multi-chamber adding element areconnected with the transmitters of the movement of the operating memberof the regulators and the negative control chambers are connected witheach other, their common output being connected through intermediatetwo-chamber comparing device with the operating member of theregulators. Due to such connection of the negative and positive controlchambers a signal is derived which is an average of the movements ofsaid operating members of the regulators. In more details, the commonoutput of the negative control chambers is connected with one of thechambers of each intermediate two-chamber comparing device, the otherchamber of which is connected with the transmitter of the movement ofthe operating member of one of the regulators, the output movableelement of this comparing device being connected with the operatingmember of the same regulator.

In spite of the fact that the afore-mentioned method and the apparatusimplementing this method have some advantages as compared to the priordescribed one they do not still provide sufficiently high accuracy andquickness of synchronization of the actuators and therefore the accuracyand quickness of the process of equalization of the load between theassociated prime movers operating in parallel. This is stipulated by thefact that, in the first place, this method and apparatus forimplementation thereof comprise two steps of signal comparison, each ofsaid steps introducing its own error into the process of synchronizationand, in the second place, in one of these comparing steps a signal isused which is the average of the movement of the operating members. Theuse of such average value accounts for comparatively low correctionsignal and results in, in general, still further decrease in the valueof the correction signal with the increase in the number of synchronizedactuators. Moreover, the use of the average value introduces itself someuncertainty into the process of synchronization. It is necessary also topoint out the fact that in the apparatus realizing said method thecommon control action is transmitted from the setting device to theregulators through an additional means and that the elementdisconnecting the comparing device from the synchronizing circuitintroduced from the purpose of more comfortable manipulation of saidapparatus comprises a lot of valve means complicating the constructionof this apparatus.

SUMMARY OF THE INVENTION

The present invention is based on the objective of developing such amethod of synchronizing the actuators of prime or secondary moversdriving a common load and of providing such a simple in design apparatusimplementing this method, as to provide a substantial decrease in thenonuniformity of the load distribution between these movers with changesof the common load on the movers or with changes of the load on one ofthem in a sufficiently wide range.

To achieve the aforesaid objective, there is provided a method ofsynchronizing actuators, each having a movable operating member andproviding control of one of the prime or secondary movers driving acommon load through varying the amount of the energy medium supplied tosaid movers, comprising the steps of measuring the movement of theoperating members of the actuators, corresponding in magnitude to saidmedium supplied and, therefore to the loads on said movers associatedwith the actuators to derive signals corresponding to the movement ofthe operating member of each actuator, and adjusting the position of theoperating member of each actuator in a direction and by an amount equalto the correction signal derived from comparison of the signalscorresponding to the movement of the operating member of each actuator,wherein, according to the invention, the correction signal is derived sothat it is proportional in magnitude to the sum of differences betweenthe signal corresponding to the movement of the operating member of anyone of the actuators and each of the signals corresponding to themovement of the operating member of the rest of the actuators.

Due to such way of producing the correction signal synchronization ofthe actuators is accomplished with higher accuracy and quickness.

To achieve the aforesaid objective, there is also provided an apparatusimplementing the above method of synchronizing actuators, comprising apressure fluid source associated with a setting device adapted to set acommon control action on the movement of the operating member of eachactuator, said movement providing the energy medium supply to the primeor secondary movers, and also associated with transmitters of themovement of the operating members of the actuators and with a comparingdevice adapted to produce a control action on the actuators, saidcomparing device being associated with the actuators and with thetransmitters of the movement of the operating members of the actuatorsand representing a multichamber adding element having a housing closedat opposite ends and accommodating a stem movable axially in oppositedirections relative to its central position and secured to a pluralityof diaphragms disposed within the housing, one part of said diaphragmshaving an effective area of each diaphragm larger than that of the otherpart, said diaphragms being mounted within the housing in such a mannerthat the diaphragms with different effective area alternate and dividethe interior of the housing into positive control chambers providing themovement of the stem off-center in one direction in response to thepressure build up therein, negative control chambers providing themovmenet of the stem in the opposite direction in response to thepressure build up therein, an inlet chamber which connects the pressurefluid source with the actuator when the stem is moved in said onedirection by the sum of the pressures in the positive control chambersexceeding the sum of the pressures in the negative control chambers, anoutlet chamber connected with an inlet chamber and communicated, whenthe stem is moved in said opposite direction by the sum of the pressuresin the negative control chambers exceeding the sum of the pressures inthe positive control chambers, with a pressure fluid drain means,wherein, in accordance with the invention, adding elements at the abovetype are additionally introduced in such a quantity that the totalnumber of the adding elements is equal to the chamber of the actuatorsto be synchronized, the inlet chamber of each adding element beingcommunicated with one of the negative control chambers of the sameadding element, one of the positive control chambers of each addingelement being connected with the output of the setting device and theoutput of the transmitter of the movement of the operating member ofeach actuator being connected with such a number of negative controlchambers of the adding element associated with the same actuator whichis one unit less than the number of synchronized actuators and with oneof the positive control chambers of the rest of the adding elements.

In the proposed apparatus of synchronizing actuators, the correctionsignal is derived and the common control signal for each actuator isapplied through one comparing device, said signals being in the samescale.

It is reasonable that the output of the transmitter of the movement ofthe operating device of each actuator be connected to correspondingcontrol chambers of the adding elements through an adjustable throttle.

Application of the adjustable throttle gives the possibility to adjustthe time constants of said transmitters.

It is reasonable also that the inlet chamber of each adding element beconnected with a respective actuator through an adjustable throttle.

This adjustable throttle gives the possibility to adjust the movement ofthe operating device of each actuator.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more apparent from the followingdescription used to illustrate preferred embodiments of the inventiontaken in conjunection with the accompanying drawings, in which:

FIG. 1 is a block-diagram of control of several prime or secondarymovers, illustrating a method of synchronizing actuators in accordancewith the present invention; and

FIG. 2 is a structural diagram of the apparatus implementing theproposed method of synchronizing actuators in accordance with thepresent invention.

BEST MODE TO CARRY OUT THE INVENTION

FIG. 1 shows a conventional view of prime or secondary movers designatedby 1a, 1b and 1c which can be both internal combustion engines andpneumatic or hydraulic engines and which, in this particular case, areDiesel engines used as a part of the marine power plant driving a commonload, namely a ship propeller 2 with which these engines arecommunicated through a reducing gear equipped with gear wheels 3. Themovers 1a, 1b and 1c are controlled through individual actuators 4a, 4band 4c respectively which can be devices of various types with movableoperating elements and which, in this particular case, are pneumaticdrive mechanisms exerting an effect on the speed governors of thesemovers.

Each actuator 4 has a movable operating member 5 connected with a fuelpump rod (not shown) which is responsible for fuel supply to therespective controlled mover 1. The common control action on theactuators 4 is effected with the help of a setting device 6 through adevice 7 which provides distribution of the control signals from thesetting device 6 and comparison of the control signals passing alongforward and feedback circuits 8 and 9, respectively. Arranged in thefeedback circuits are transmitters 10 of the movement of the operatingmembers 5 of the actuators 4. The transmitters 10 are pneumatic devicestransforming translational movement of the operating member 5 into apneumatic signal. The setting device 6 is also a device of pneumatictype transforming rotation of its operating member 11 into a pneumaticsignal and therefore the circuits 8 and 9 are ordinary pipes as theywill be further called.

The proposed method of synchronizing actuators comprises the followingsteps. During operation of the movers 1 the fuel is continuouslysupplied thereto. With the change in the load on the movers 1 in courseof their operation the amount of fuel supplied to said movers is variedby respective actuators 4 on account of the movement of the fuel pumprods of each mover 1 and therefore the operating members 5 associatedwith the actuators 4. The movement of the operating members 5a, 5b and5c corresponding in magnitude to the change in the load on each mover 1is sensed by the transmitters 10a, 10b and 10c respectively to derive insaid transmitters respective pneumatic signals applied through pipes 9a,9b and 9c to the comparing device 7 which compares the signalscorresponding to the movement of the operating member 5 of each actuator4 to derive therefrom a respective correction pneumatic signal. In theproposed method this correction signal is formed so that it isproportional in magnitude to the sum of the differences between thesignal corresponding to the movement of the operating member 5 of anysingle actuator 4 and each signal corresponding to the movement of theoperating member 5 of the rest of said actuators. The derived correctionsignals are used then to adjust the position of the operating member 5of each actuator 4 in a direction and by an amount equal to said signalso as to equalize the loads on the movers 1, the correction signalsbeing applied through the pipes 8.

FIG. 1 shows for ease of illustration three movers and three associatedactuators. It is necessary to understand, however, that the method ofsynchronizing actuators in accordance with the present invention can beused for synchronizing any number of actuators.

The apparatus implementing the proposed method, illustrated in FIG. 2,comprises pneumatic one-way actuators 4a, 4b and 4c each having acylinder with an operating volume 12 and a piston loaded by a spring 13and having a rod, which is an operating member 5 of this actuator. Theoperating member 5 of each actuator 4 is associated through a lever 14with one of the movement transmitters 10 which are pneumomechanicalsensitive devices of a diaphragm type with force compensation. Thedescribed apparatus further comprises a pressure fluid source 15 whichis an aircompressor producing a pressure of about 0.137 MPa (1.4kgf/cm²) and equipped with a pressure fluid drain means 16, andmultichamber adding elements 17a, 17b and 17c equal in number toactuators 4 to be synchronized.

Each multichamber adding element 17 comprises a cylindrical housing 18closed at opposite ends and made of bowl-shaped elements 19 centrallyapertured. The bowl-shaped elements 19 are mounted along the verticalextent of the housing 18 in pairs in such a manner as to face each otherin each pair by their bottom parts, each pair of said elements formingin the wall of the housing 18 a circular projection toward the axis ofthe housing 18 with a circular groove between such pairs. Disposedwithin the housing 18 is a central stem 20 movable axially in oppositedirections relative to its center position and a number of flexiblediaphragms 21 secured to said stem 20 and axially spaced therein. Eachone of the diaphragms 21 clamped around their peripheries to the wall ofthe housing 18 is secured at its center to the stem 20 by the sleeves 22mounted on said stem. The sleeves 22 have T-shaped longitudinal sectionand are mounted along the vertical extent of the stem 20 in pairs insuch a manner as to face each other in each pair by their wider parts,the diaphragms 21 being arranged just between the faces of said parts.Each pair of the sleeves 22 forms on the stem 20 a circular projectiontowards the wall of the housing 18, a groove being formed on the stem 20between such pairs. The central stem 20 is mounted within the housing 18is such a manner that the circular projections of this stem come intothe circular grooves of the wall of the housing 18 not contactinghowever the surfaces of these grooves. With this arrangement one part ofthe diaphragms 21 has its centrals secured to the stem 20 at the site ofits circular projection, while their peripheries are secured to the wallof the housing 18 at the site of its circular groove and the other partof the diaphragms 21 has it vice versa. As a result, in one part of thediaphragms 21 an effective area of one diaphragm is larger than that ofthe other part and the diaphragms with different effective areas arearranged alternatively. The sleeves 22 and the diaphragms 21 mountedtherebetween are clamped together by a nut 23 screwed onto the stem 20.

The diaphragms 21 divide the interior of the housing 18 into severalcontrol chambers, namely 24, 25, 26, 27, 28 and 29 disposed in themiddle partion of the housing 18. The chambers 24, 26 and 28 arepositive control chambers providing the movement of the stem 20 in onedirection relative to its central position, i.e. downwardly (referenceto the drawing) in response to the pressure build up therein, and thechambes 25, 27 and 29 are negative control chambers providing themovement of the stem 20 in the opposite direction, i.e. upwardly(reference to the drawing) in response to the pressure build up therein.The control chambers 24, 25, 26, 27, 28 and 29 are made closed and areprovided with inlet passages 30, 31, 32, 33, 34 and 35 respectively.

Each adding element 17 is provided with an inlet chamber 36 and anoutlet chamber 37 disposed within the housing 18 at the ends thereof.The inlet 36 and the outlet 37 chambers are made as fluid-runningchambers and have inlet passages 38 and 39 and outlet passages 40 and 41respectively. Mounted in the inlet chamber 36 is a nozzle 42 loaded by aspring 43 and having a radial passage 44 and an axial passage 45 tosupply the pressure fluid. The nozzle 42 is provided with an adjustingscrew 46 adapted to adjust the nozzle 42 in initial position and therebyto set the value of the operating pressure applied to the adding element17. Similar to that, the outlet chamber 37 includes a nozzle 47 loadedby a spring 48 and having a radial passage 49 and an axial passage 50and an adjusting screw 51, the outlet ends of the nozzles 42 and 47facing the ends of the movable stem 20.

Described above is one of the adding elements 17, namely, and addingelement 17a presented as a sectional view in FIG. 2. The adding elements17b and 17c are shown on this drawing schematically for they are exactlyof the same construction as the adding element 17a.

In each one of the adding elements 17, the inlet passage 38 of the inletchamber 36 is connected by the pipe 52 with the pressure fluid source 15and the outlet passage 40 of this chamber is connected with the inletpassage 39 of the outlet chamber 37 and with one of the negative controlchambers, namely with the inlet passage 35 of the chamber 29.Communication of the inlet chamber 36 with the negative control chamber39 in each adding element 17 is necessary to form negative feedbackproviding analogue character of the output signal of said elements. Acommon output 53 of each adding element 17 is connected through the pipe8 with the operating volume 12 of the respective actuator 4 through anadjustable throttle 54. The latter has an adjustable cross-section dueto which the speed of the pressure build up can be changed at the inletto the operating volume 12 and thereby the time of operation of eachactuator 4 and the associated adding element 17 matched. Moreover, ineach adding element 17 the outlet passage 41 of the outlet chamber 37 isconnected through a pipe 55 with the pressure fluid drain means 16 toallow the air escape from this chamber to the atmosphere, and the inletpassage 34 of the positive control chamber 28 is connected through apipe 56 with the output of the setting device 6.

The output of the transmitter 10a of the movement of the operatingdevice 5a of the actuator 4a is connected by the pipe 9a through anadjustable throttle 57a, which is similar to the throttles 54 and isadapted to match the time constants of the transmitter 10a and theadding element 17a, with the inlet passage 31 of the negative controlchamber 25 and with the inlet passage 33 of the negative control chamber27 of the same element, as well as with the positive control chamber 24of the adding element 17b an with the positive control chamber 26 of theadding element 17c. Similar to that the output of the transmitter 10b isconnected by the pipe 9b through an adjustable throttle 57b, same as thethrottles 57a, with the negative control chambers 25 and 27 of theadding element 17b, with the positive control chamber 24 of the addingelement 17a and with the similar chamber 24 of the adding element 17c,while the output of the transmitter 10c is connected by the pipe 9cthrough an adjustable throttle 57c with the negative control chambers 25and 27 of the adding element 17c and with the positive control chambers26 of the adding elements 17a and 17b. In other words, irrespective ofthe number of synchronized actuators 4 the output of the transmitter 10of the movement of the operating device 5 of each actuator 4 isconnected with the same number of negative control chambers of theadding element 17 associated with this particular actuator 4, saidnumber being one unit less than the number of synchronized actuators 4,and with one of the positive control chambers of the rest of the addingelements 17.

The setting device 6 is connectd with the pressure fluid source 15 bymeans of a pipe 58, and the transmitters 10 of the movement of theoperating members 5 of the actuators 4 are connected by a pipe 59 withsaid source through a cut-out valve 60 providing disconnection, ifnecessary, from the supply of said transmitters as well as opening thefeedback circuit in the synchronizing circuit of the actuators 4 andthereby putting said actuators out of synchronous operation. The cut-outvalve 60 makes possible to switch off the synchronizing circuit and tocontinue the operation of the actuators 4 in case the failure occurs inthe transmitters 10, in the pipes, etc. or in any other particularcases.

The apparatus for synchronizing actuators of prime or secondary moversin accordance with the present invention operates as follows.

Before the synchronizing apparatus is switched on the movers 1 (FIG. 1)are separately started and set for the preliminary cycle of operationwithout loading. At this stage the transmitters 10 are not energized andtherefore the synchronizing circuit of said actuators is not underoperation. To make the movers 1 to work at the required speed at thisstarting stage the operating member 11 of the setting device 6 isadjusted to a corresponding position, the pneumatic signal from theoutput of the setting device 6 being transmitted through the pipe 56(FIG. 2) to the positive control chambers 28 of all the adding elements17. As a result the stem 20 is moved downwardly (here and furtheron inthe text with reference to the plane of the drawing) under the effect ofthe pressure applied to the chambers 28, due to which in the inletchambers 36 the clearance between the nozzle 42 and the end of the stem20 facing thereof is increased and in the outlet chambers 37 theclearance between the nozzle 47 and the end of the stem 20 facingthereof is decreased. In other words, the nozzle 42 is opened and thenozzle 47 is closed, whereby at the output 40 of the inlet chambers 36the air pressure applied from the source 15 through the pipe 52 andadmitted to these chambers through the inlet passages 38, radial passage44 and axial passage 45 starts to build up, this process being promotedalso by the fact that the escape of air to the atmosphere from theoutlet chambers 37 through the axial passage 50, radial passage 49 andoutlet passage 41 decreases herewith. The stem 20 in each adding element17 occupies, due to the negative feedback through the negative controlchamber 29, a position providing the pressure at the common outputs 53a,53b and 53c equal to the pressures applied to the positive controlchambers 28, i.e. at this stage the adding elements 17 operate asrepeaters of the signal transmitted from the setting device 6.

The pneumatic signals derived in the adding elements 17 are applied viathe pipes 8a, 8 b and 8c through the adjustable throttles 54a, 54b and54c to the operating volumes 12a, 12b and 12c of the actuators 4a, 4band 4c, respectively. The rods, or the operating members 5 of theseactuators start to move downwardly compressing the springs 13. The fuelsupplied to the movers 1 (FIG. 1) corresponds in magnitude to themovement of the operating members 5. However, common equal action fromthe setting device 6 on the actuators 4 does not result in equalmovement of their operating members 5 due to unavoidable difference incharacteristics of the elements constituting the circuits oftransmission of this action and therefore the movers 1 receive differentsettings for speed. But since the movers 1 cannot have different speeddue to rigid connection therebetween, some of them are overloaded whenthe load is applied thereto while the others are underloaded relative totheir rates load. This can be accompanied by variations in the resultingunderloading or overloading leading to injurious consequences mentionedabove. Therefore prior to loading the movers 1, synchronization ofactuators 4 is carried out by energizing the transmitters 10 through thevalve 60 (FIG. 2) to equalize the loads on all of said engines.

When the valve 60 is actuated, the movement of the operating members 5of the actuators 4 is transmitted through the levers 14 to the movableelements of the transmitters 10 developing corresponding output signals.The output pneumatic signals of the transmitter 10a are applied in theadding elements 17a to the negative control chambers 25 and 27, in theadding element 17b, to the positive control chamber 24, and in theadding element 17c, to the positive control chamber 26. The outputpneumatic signals from the transmitter 10b are applied in the addingelement 17b to the negative control chambers 25 and 27, and in theelements 17a and 17c, to the positive control chambers 24, and theoutput signals from the transmitter 10c are applied in the element 17cto the negative control chambers 25 and 27, and in the elements 17a and17b, to the positive control chambers 26. In the case when the movementof all the operating members 5 is equal, the forces from thetransmitters 10 on each one of the adding elements 17 are also equal.Therefore the pressures in the control chambers of the adding element 17are mutually compensated, and the stems 20 of the adding elements 17 donot move, whereby only the pneumatic signal from the setting device 6passes into the operating volume 12 of each actuator 4.

When, due to any reasons, the load on any of the movers 1 (FIG. 1)increases, for example, on the mover 1a, this engine consumes moe fueland the operating member 5a of the actuator 4a moves downwardly, whilethe position of the operating members 5b and 5c of the actuators 4b and4c at that moment remains unchanged. As a result, the pressure at theoutput of the transmtter 10a increases. This build up of the pressure istransmitted through the pipe 9a to the control chambers 25 and 27 of theadding element 17a, and the pressure at the common output 53a of thiselement decreases since said control chambers are negative ones. Thispressure drop is transmitted through the pipe 8a to the operating volume12a of the actuator 4a, whereby its operating member 5a moves upwardlythereby decreasing the fuel supply to the associated mover 1a, which isaccompanied by the pressure drop at the output of the transmitter 10a.

Simultaneously the signal of the pressure build up from the output ofthe transmitter 10a is applied to the positive control chamber 24 of theadding element 17b, causing the pressure build up at the output 53b ofsaid element. This build up of the pressure is transmitted through thepipe 8b to the operating volume 12b of the actuator 4b whereby itsoperating member 5b is moved downwardly thereby increasing the fuelsupply to the associated mover 1b. This is accompanied by the pressurebuild up at the output of the transmitter 10b.

Besides, the signal of the increased pressure from the output of thetransmitter 10a is applied to the positive control chamber 26 of theelement 17c which also results in the pressure build up at the output53c of this element, this pressure build up being transmitted throughthe pipe 8c to the operating volume 12c of the actuator 4c, whereby itsoperating member 5c moves downwardly thereby increasing the fuel supplyto the associated mover 1c. This is accompanied by the pressure build upat the output of the transmitter 10c.

Thus, when the load on the mover 1a is increased, the regulating effectexerted on the actuator 4a from the adding element 17a tends to decreasethe fuel supply to that mover, while the regulating effect exerted onthe actuators 4b and 4c from the adding elements 17b and 17c tends toincrease the fuel supply to the movers 1b and 1c. The process ofchanging the pressures at the common outputs 53 of the adding elements17, and thereby the position of the operating members 5 of the actuators4, is over when, as a result of the movement of these operating membersin the direction towards each other, the pressures at the output of thetransmitters 10a, 10b and 10c are equalized. This brings toredistribution of the amount of fuel supplied to each mover 1 andequalization of the loads on said movers. The synchronizing apparatusthus decreases the load on the overload mover 1a and increases the loadon the underloaded movers 1b and 1c.

Assume now that the load is increased on the movers 1a and 1b by thesame amount. These movers start to consume more fuel and the operatingmembers 5a and 5b respectively of the actuators 4a and 4b are moveddownwardly. As a result, the pressure at the inputs of the transmitters10a and 10b is increased practically by the same amount, and thispressure build up at the output of said transmitters is transmittedthrough the pipes 9a and 9b, as described above, to the control chambersof all the adding elements 17.

In the adding element 17a the signals of the pressure build up areapplied to the negative control chambers 25 and 27 from the transmitter10a and to the positve control chamber 24 from the transmitter 10b.Since two of these three chambers are negative control chambers, thepressure at the common output 53a of the adding element 17a decreasescausing the movement of the operating member of the actuator 4a upwardlyand thereby decreasing fuel supply to the mover 1a. This is accompaniedby the decrease in the pressure at the output of the transmitter 10a.

In the adding element 17b the signal of the pressure build up from thetransmitter 10b is applied to the negative control chambers 25 and 27and from the transmitter 10a, to the positive control chamber 24. As aresult, similar to the adding element 17a, the pressure at the commonoutput 53b of the element 17b decreases causing also the movement of theoperating member 5b of the actuator 4b upward and thereby decreasing thefuel supply to the mover 1b. This is accompanied by the decrease in thepressure at the output of the transmitter 10b.

In the adding element 17c the signals of the pressure build up from thetransmitter 10b are applied to the positive control chamber 24 and fromthe transmitter 10a to the positive control chamber 26. Since both thesecontrol chambers are positive, the pressure at the output 53c of theelement 17c increases causing the movement of the operating member 5cdownward thereby increasing the fuel supply to the mover 1c. This isaccompanied by the pressure build up at the output of the transmitter10c.

Thus, when the load on the movers 1a and 1c increases the regulatingeffect exerted on the actuators 4a and 4b from the adding elements 17aand 17b tends to decrease the fuel supply to said movers, while theregulating effect exerted on the actuator 4c from the adding element 17ctends to increase the fuel supply to the mover 1c. The process ofchanging the position of the operating members 5 of the actuators 4 isover when, as a result of the movements of said operating members in thedirections towards each other, the loads on the movers 1 are equalized.

Other changes in the loads on the movers 1 result in the processessimilar to those described above.

In the proposed apparatus for synchronizing actuators the setting device6 and the transmitters 10 of the movement of the operating members 5 ofsaid actuators produce the pneumatic signals in one pressure scale.Change of the pressure at the output, respectively, of the settingdevice 6 and the transmitters 10 corresponds to the change in the speedof the movers 1 from zero to the rated value, and also to the change inthe amount of the fuel supplied therein from the value corresponding tothe idle operation to the rated value. This change lies within the rangefrom 19.6 to 98.0 KPa (from 0.2 to 1.0 kgf/cm²). To illustrate theoperation of the described synchronizating apparatus an equation can bemade in accordance with FIG. 2 which defines the pressures on the commonoutputs 53 of the three adding elements 17. These equations are:

    P.sub.A =p.sub.o -p.sub.1 -p.sub.1 +p.sub.2 +p.sub.3 =p.sub.o +(p.sub.2 -p.sub.1)+(p.sub.3 -p.sub.1),                             (1)

    P.sub.B =p.sub.o -p.sub.2 -p.sub.2 +p.sub.1 +p.sub.3 =p.sub.o +(p.sub.1 -p.sub.2)+(p.sub.3 -p.sub.2),                             (2)

    P.sub.C =p.sub.o -p.sub.3 -p.sub.3 +p.sub.1 +p.sub.2 =p.sub.o +(p.sub.1 -p.sub.3)+(p.sub.2 -p.sub.3)                              (3)

where

P_(A), P_(B), P_(C) are output pneumatic signals of the adding elements17a, 17b and 17c respectively applied to the actuators 4a, 4b and 4c,

P_(o) is an output pneumatic signal of the setting device 6,

p₁, p₂, p₃ are output pneumatic signals of the transmitters 10a, 10b and10c respectively, their signs corresponding to the type of the controlchambers of the adding element 17 whereto said signals are applied.

In the first part of the equations (1) to (3) the member p_(o) definesthe control action of the actuators 4 and the rest of the members definethe corrective effect on said actuators.

It is not difficult to make sure that for "n" of the actuators 4 theequations of the summing effect on each of said actuators have thefollowing form:

    P.sub.A =p.sub.o +p.sub.2 +p.sub.3 + . . . +p.sub.n -(n-1)p.sub.I, (4)

    P.sub.B =p.sub.o +p.sub.1 +p.sub.3 + . . . +p.sub.n -(n-1)p.sub.2 (5),

etc.

The method of synchronizing actuators and the apparatus implementingsaid method in accordance with the present invention has the followingadvantages.

First of all it is necessary to note that the proposed method andapparatus provide sufficiently high accuracy and quickness ofsynchronization of the actuators. Application of this method andapparatus implementing the same allows to obtain the degree of mismatchof the position of the operating member of the synchronized actuatorsand, correspondingly, the speeds or moments of the associated objects ofadjustment not above 1 percent. High accuracy and quickness ofsynchronization are achieved due to the fact that:

in the first place, the correction signal applied simultaneously to allthe actuators in the proposed synchronizing circuit is greater inmagnitude than that in the known circuits because in this circit saidsignal is defined by the sum of differential signals,

in the second place, in the proposed synchronizing circuit thecorrection signal for each synchronized actuator is formed only in oneadding element, through which, moreover, the signal of common controlaction is also applied to said actuator, and

in the third place, in the course of movement of the operating membersof the actuators to the position corresponding to its synchronizedstate, these operating members move in the directions toward each otherand therefore their tracks are not large.

High degree of equalization of the load on the movers associated withthe actuators achieved due to high accuracy and quickness ofsynchronization of said actuators prevents long lasting overloading ofthe movers which increases the service life of these movers and reducesthe probability of failures, as well as decreases the fuel consumption.

Besides, it is necessary to note that the proposed synchronizingapparatus comprises minimum number of comparing devices which arestandard adding elements applied in industrial pneumoautomation. Thisallows to develope a simple, reliable and easily unified construction ofthe synchronizing apparatus easy for maintenance and for repair.

It is necessary also to point out to the fact that the proposed methodand apparatus can be used for synchronizing actuators of many types ofprimary and secondary movers such as, for example, the internalcombustion engines, pneumatic engines, hydraulic engines, etc.

While particular embodiments of the invention have been shown anddescribed, various modifications thereof will be apparent to thoseskilled in the art and therefore it is not intended that the inventionbe limited to the description of the proposed method of synchronizingactuators and of the apparatus implementing the same or to the detailsthereof and the departures may be made therefrom within the spirit andscope of the invention as defined in the appended claims.

COMMERCIAL APPLICABILITY

The present invention can most advantageously be used in multiple-unittransport power plants comprising Diesel engines or turbines andproviding the operation of an electric generator requiring that thespeed of the power plant engines be kept at a constant level.

We claim:
 1. An apparatus for synchronizing actuators, comprising apressure fluid source associated with a setting device adapted to set acommon control action on the movement of the operating member of eachactuator, said movement providing the energy medium supply to the primeor secondary movers, and also associated with transmitters of themovements of the operating members of the actuators and with a comparingdevice adapted to produce a control action on the actuators, saidcomparing device being associated with the actuators and with thetransmitters and representing a multichamber adding element having ahousing closed at opposite ends and accommodating a stem movable axiallyin opposite directions relative to its center position and secured to aplurality of diaphragms disposed within the housing, one part of saiddiaphragms having an effective area of each diaphragm larger than thatof the other part, said diaphragms being mounted within the housing insuch a manner that the diaphragms with different effective areaalternate and divide the interior of the housing into positive controlchambers providing the movement of the stem off center in one directionin response to the pressure build up therein, into negative controlchambers providing the movement of the stem in the opposite direction inresponse to the pressure build up therein, an inlet chamber whichconnects the pressure fluid source with the actuator when the stem ismoved is said one direction by the sum of the pressures in the positivecontrol chambers exceeding the sum of the pressures in the negativecontrol chambers, an outlet chamber connected with an inlet chamber andcommunicated, when the stem is moved in said opposite direction by thesum of the pressures in the negative control chambers exceeding the sumof the pressures in the positive control chambers, with a pressure fluiddrain means, characterized in that it further comprises adding elements(17) of the above type and in such a quantity that the total number ofthe adding elements (17) is equal to the number of synchronizedactuators (4), the inlet chamber (36) of each adding element (17) beingcommunicated with one of the negative control chambers (25), (27), (29)of the same adding element (17), one of the positive control chambers(24,), (26), (28) of each adding element (17) being connected with theoutput of the setting device (6) and the output of the transmitter (10)of the movement of the operating member (5) of each actuator (4) beingconnected with such a number of negative control chambers (25), (27),(29) of the adding element (17) associated with the same actuator (4),which is one unit less than the number of synchronized actuators (4),and with one of the positive control chambers (24), (26), (28) of therest of the adding elements (17).
 2. An apparatus as set forth in claim1, characterized in that the output of the transmitted (10) of themovement of the operating member (5) of each actuator (4) is connectedto the respective control chambers of the adding elements (17) throughan adjustable throttle (57).
 3. An apparatus as set forth in claim 1 or2, characterized in that the inlet chamber (36) of each adding element(17) is connected to the respective actuator (4) through an adjustablethrottle (54).